A Compact Multi-Band Monopole Antenna using Single Metamaterial for WLAN/WiMAX Applications

In this paper, a tri-band printed monopole antenna with electrically coupled metamaterial units is proposed and investigated. The proposed antenna is designed to cover WLAN/WiMAX applications. The structure consists of a printed strip line and two double metamaterial unit cells of different size placed near the monopole antenna on opposite sides. Each unit cell exhibits a negative permeability over the resonance frequency at 2.5 GHz and 3.62 GHz, which produces magnetic couplings with the monopole antenna. The proposed structure was fabricated and measured. The measured -10 dB bandwidth for the reflection coefficient is from 2.47GHz-2.51GHz, 3.59GHz-3.69GHz, and 5.3GHz - 7.2 GHz, which are suitable for (WLAN: 2.4-2.484, 5.15-5.35, and 5.725-5.85 GHz) and (WiMAX: 2.5-2.69, 3.4-3.8, and 5.25-5.85 GHz) band Applications. By using the switches across the gap of proposed-MTM unit cell, the effect of this unit deactivated and its resonance frequency will disappear. Hence, the proposed antenna maintains the omnidirectional radiation pattern.